Shroud hanger assembly

ABSTRACT

A shroud hanger assembly or shroud assembly is provided for a gas turbine engine wherein a hanger includes a radially depending and axially extending arm. The arm or retainer engages a pocket formed in a shroud so as to retain the shroud in a desired position relative to the hanger. An aft retaining structure is provided on the hanger and provides a seat for a seal structure which biases the retainer so that the arm of the hanger maintains engagement in the shroud pocket. A baffle may be utilized at the hanger to cool at least some portion of the shroud.

CROSS-REFERENCE TO RELATED DOCUMENTS

The present application is a divisional of prior filed U.S. patentapplication Ser. No. 15/318,114 filed Dec. 12, 2016, which claimspriority to PCT application serial number PCT/US2015/029236, filed on 5May 2015, which claims priority to U.S. Provisional Patent ApplicationSer. No. 62/011,241 titled “SHROUD HANGER ASSEMBLY” filed on 12 Jun.2014, the disclosures of which are incorporated by reference herein.

TECHNICAL FIELD

The present embodiments relate to a shroud hanger assembly for use in agas turbine engine. More specifically, present embodiments relate to,without limitation, a shroud hanger assembly utilizing a shroud havingat least one pocket which is retained by an arm depending from theretainer and further comprising a spring seal biasing the shroud.

BACKGROUND

A gas turbine engine includes a turbomachinery core having a highpressure compressor, combustor, and high pressure turbine (“HPT”) inserial flow relationship. The core is operable in a known manner togenerate a primary gas flow. The high pressure turbine includes annulararrays (“rows”) of stationary vanes or nozzles that direct the gasesexiting the combustor into rotating blades or buckets. Collectively onerow of nozzles and one row of blades make up a “stage”. Typically two ormore stages are used in serial flow relationship. These componentsoperate in an extremely high temperature environment, and must be cooledby air flow to ensure adequate service life.

Due to operating temperatures within the primary flow path of the gasturbine engine, it may be beneficial to utilize materials with lowcoefficient of thermal expansion. For example, to operate effectively insuch strenuous temperature and pressure conditions, composite materialshave been suggested and, in particular for example, ceramic matrixcomposite (CMC) materials. These low coefficient of thermal expansionmaterials have higher temperature capability than metallic parts. Thehigher operating temperatures within the engine result in higher engineefficiency and these materials may be lighter weight than traditionallyused metals. However, such ceramic matrix composite (CMC) havemechanical properties that must be considered during the design andapplication of the CMC. CMC materials have relatively low tensileductility or low strain to failure when compared to metallic materials.Also, CMC materials have a low coefficient of thermal expansion whichdiffers significantly from metal alloys used as restraining supports orhangers for CMC type materials.

One use for low ductility material is in a turbine shroud. However,various problems are known to exist with shroud hanger assemblies. Forexample, while CMC may be beneficial for use with shrouds, the hangermay alternatively be formed of metal alloy. Therefore, the issue ariseswhich has herertofore precluded use of low coefficient of thermalexpansion materials in combination with metallic, that is how to dealwith differential expansion between adjacent components.

Some hanger assemblies have utilized bolts and retainer structuresadding components and weights.

It may also be beneficial to ensure that the shroud hanger assembly isproperly sealed. Such sealing issues may develop due to thermal growthof parts of differing materials. Such growth may result in gaps betweensealing surfaces and may be undesirable. Therefore, a sealing structureis needed due to the differential growth. Such structure also addsweight.

Additionally, the use of multi-piece hanger constructions made of afirst material which may differ from the low ductility, low coefficientof thermal expansion second material defining a shroud may also resultin air leakage which may be undesirable. It may be beneficial toovercome these and other deficiencies to provide a shroud hangerassembly which provides for sealing of the interfaces between parts ofdiffering material and biases the parts to compensate for differentialthermal growth therebetween.

The information included in this Background section of thespecification, including any references cited herein and any descriptionor discussion thereof, is included for technical reference purposes onlyand is not to be regarded subject matter by which the scope of thedisclosure is to be bound.

BRIEF DESCRIPTION

A shroud hanger assembly or shroud assembly is provided for a gasturbine engine wherein a hanger includes a radially depending andaxially extending arm. The arm or retainer engages a pocket formed in ashroud so as to retain the shroud in a desired position relative to thehanger. An aft retaining structure is provided on the hanger andprovides a seat for a seal structure which biases the retainer so thatthe arm of the hanger maintains engagement in the shroud pocket. Abaffle may be utilized at the hanger to cool at least some portion ofthe shroud.

According to some embodiments, a shroud hanger and shroud assemblycomprises a shroud hanger having a forward leg, a rearward leg and a webextending between the forward and rearward legs, an arm depending fromthe web and having an axially extending portion, a shroud formed of alow thermal coefficient of thermal expansion material extending from theforward leg toward the rearward leg and having a pocket for receivingthe axially extending portion, a retainer depending from the rearwardleg and clipped thereto, and, a conformal seal applying an axial forceto the shroud in an axial direction to maintain the retainer in thepocket.

This Brief Description is provided to introduce a selection of conceptsin a simplified form that are further described below in the DetailedDescription. This Brief Description is not intended to identify keyfeatures or essential features of the claimed subject matter, nor is itintended to be used to limit the scope of the claimed subject matter.All of the above outlined features are to be understood as exemplaryonly and many more features and objectives of the structures and methodsmay be gleaned from the disclosure herein. A more extensive presentationof features, details, utilities, and advantages of embodiments of thepresent invention is provided in the following written description ofvarious embodiments of the invention, illustrated in the accompanyingdrawings, and defined in the appended claims. Therefore, no limitinginterpretation of the Brief Description is to be understood withoutfurther reading of the entire specification, claims and drawingsincluded herewith.

BRIEF DESCRIPTION OF THE ILLUSTRATIONS

The above-mentioned and other features and advantages of theseembodiments, and the manner of attaining them, will become more apparentand the embodiments will be better understood by reference to thefollowing description taken in conjunction with the accompanyingdrawings, wherein:

FIG. 1 is a side section view of an exemplary gas turbine engine;

FIG. 2 is an isometric view of the shroud hanger assembly removed fromthe gas turbine engine;

FIG. 3 is a side section view of the assembly of FIG. 2;

FIG. 4 is a lower isometric view of the hanger with the shroud removed;

FIG. 5 is an isometric view of an exemplary shroud removed from thehanger; and,

FIG. 6 is a side section view of an alternative embodiment wherein theshroud has multiple pockets and the hanger has multiple retaining arms.

DETAILED DESCRIPTION

It is to be understood that the depicted embodiments are not limited inapplication to the details of construction and the arrangement ofcomponents set forth in the following description or illustrated in thedrawings. The depicted embodiments are capable of other embodiments andof being practiced or of being carried out in various ways. Each exampleis provided by way of explanation, not limitation of the disclosedembodiments. In fact, it will be apparent to those skilled in the artthat various modifications and variations may be made in the presentembodiments without departing from the scope or spirit of thedisclosure. For instance, features illustrated or described as part ofone embodiment may be used with another embodiment to still yieldfurther embodiments. Thus it is intended that the present disclosurecovers such modifications and variations as come within the scope of theappended claims and their equivalents.

Embodiments of a shroud hanger assembly are depicted in FIGS. 1-6. Theshroud hanger assembly includes a hanger having a structural arrangementwherein the hanger provides a radial retaining feature for the shroud.According to one embodiment, the shroud is formed having a pocket whichis engaged by an arm depending from the hanger web and extends axiallyso as to be positioned in the shroud pocket. A biasing force may beapplied to the shroud in order to retain the shroud pocket in engagementwith the arm. According to some embodiments, the hanger may havemultiple arms and the shroud may have multiple pockets.

Also, it is to be understood that the phraseology and terminology usedherein is for the purpose of description and should not be regarded aslimiting. The use of “including,” “comprising,” or “having” andvariations thereof herein is meant to encompass the items listedthereafter and equivalents thereof as well as additional items. Unlesslimited otherwise, the terms “connected,” “coupled,” and “mounted,” andvariations thereof herein are used broadly and encompass direct andindirect connections, couplings, and mountings. In addition, the terms“connected” and “coupled” and variations thereof are not restricted tophysical or mechanical connections or couplings.

As used herein, the terms “axial” or “axially” refer to a dimensionalong a longitudinal axis of an engine. The term “forward” used inconjunction with “axial” or “axially” refers to moving in a directiontoward the engine inlet, or a component being relatively closer to theengine inlet as compared to another component. The term “aft” used inconjunction with “axial” or “axially” refers to moving in a directiontoward the engine nozzle, or a component being relatively closer to theengine nozzle as compared to another component.

As used herein, the terms “radial” or “radially” refer to a dimensionextending between a center longitudinal axis of the engine and an outerengine circumference. The use of the terms “proximal” or “proximally,”either by themselves or in conjunction with the terms “radial” or“radially,” refers to moving in a direction toward the centerlongitudinal axis, or a component being relatively closer to the centerlongitudinal axis as compared to another component. The use of the terms“distal” or “distally,” either by themselves or in conjunction with theterms “radial” or “radially,” refers to moving in a direction toward theouter engine circumference, or a component being relatively closer tothe outer engine circumference as compared to another component.

As used herein, the terms “lateral” or “laterally” refer to a dimensionthat is perpendicular to both the axial and radial dimensions.

All directional references (e.g., radial, axial, proximal, distal,upper, lower, upward, downward, left, right, lateral, front, back, top,bottom, above, below, vertical, horizontal, clockwise, counterclockwise)are only used for identification purposes to aid the reader'sunderstanding of the present disclosure, and do not create limitations,particularly as to the position, orientation, or use of embodiments ofthe invention. Connection references (e.g., attached, coupled,connected, and joined) are to be construed broadly and may includeintermediate members between a collection of elements and relativemovement between elements unless otherwise indicated. As such,connection references do not necessarily infer that two elements aredirectly connected and in fixed relation to each other. The exemplarydrawings are for purposes of illustration only and the dimensions,positions, order and relative sizes reflected in the drawings attachedhereto may vary.

Referring now to FIG. 1, a schematic side section view of a gas turbineengine 10 is shown. The function of the turbine is to extract energyfrom high pressure and temperature combustion gases and convert theenergy into mechanical energy for work. The turbine 10 has an engineinlet end 12 wherein air enters the core or propulsor 13 which isdefined generally by a compressor 14, a combustor 16 and a multi-stagehigh pressure turbine 20 all located along an engine axis 26.Collectively, the propulsor 13 provides power during operation. The gasturbine engine 10 may be used for aviation, power generation,industrial, marine or the like.

In operation, air enters through the air inlet end 12 of the engine 10and moves through at least one stage of compression where the airpressure is increased and directed to the combustor 16. The compressedair is mixed with fuel and burned providing the hot combustion gas whichexits the combustor 16 toward the high pressure turbine 20. At the highpressure turbine 20, energy is extracted from the hot combustion gascausing rotation of turbine blades which in turn cause rotation of theshaft 24. The shaft 24 passes toward the front of the engine to continuerotation of the one or more compressor stages 14, a turbofan 18 or inletfan blades, depending on the turbine design. The turbofan 18 isconnected by the shaft 28 to a low pressure turbine 21 and createsthrust for the turbine engine 10. The low pressure turbine 21 may alsobe utilized to extract further energy and power additional compressorstages.

Present embodiments are at least directed to a shroud hanger assembly 30which is shown generically. The shroud hanger assembly 30 may beutilized to define a flow path adjacent to rotating parts such asturbine blades 20, 21 or blades within a compressor 14. The shroudhanger assembly 30 is shown schematically in the schematic FIG. 1 view.The assembly 30 may be disposed at a radially outward end of the turbine20, 21 blades or the compressor 14 blades. As the blades of the turbineor compressor rotate, a shroud 50 (FIG. 2) in the assembly provides aflow path boundary.

Referring now to FIG. 2, an isometric view of an exemplary shroud hangerassembly 30 is depicted. The assembly 30 comprises a hanger 32 andshroud 50 which is mounted within the hanger 32 and a retainer 60 thatis utilized to provide a spring seat for biasing force the shroud 50into an engaged position with the hanger 32 precluding the possibilityof the shroud 50 inadvertently falling radially downward from the hanger32.

The hanger 32 may be a one-piece hanger or may be a multi-piece hangerassembly. The hanger 32 provides a position and structure to mount theshroud 50 in a fixed location. The shroud 50 provides an outer flowpathfor the turbine or compressor. The hanger 32 is disposed radiallyoutward of a turbine or compressor blade which rotates and has aradially outward position adjacent to the shroud 50. In the instantembodiment, the hanger 32 comprises a first tab 38 and a second tab 40.The tabs 38, 40 provide a structure which may be used to mount thehanger 32 to the engine casing. Depending from the first tab 38 is a leg39 and depending from the second tab 40 may be a second leg 41. The tabs38, 40 are shown extending in an axial direction but may alternativelybe formed to extend at angles to the purely axial direction. Further,the tabs 38, 40 are shown extending from the forward to an aftdirection. However, according to some alternatives, the tabs 38, 40 maybe formed to extend in an aft to forward direction.

The legs 39, 41 may extend from the tabs 38, 40 in a purely radialdirection or may be at an angle to the purely radial direction.

A web 42 extends from the first leg 39 toward the second leg 41 and thesecond tab 40. The web 42 defines a ceiling for the shroud such that acavity 46 is formed by a portion of the first leg 39, at least a portionof the second leg 41 and the web 42.

The hanger 32 may be formed of various materials. According to someembodiments, the hanger 32 may be formed of a metallic material whichhas a relatively higher coefficient of thermal expansion. For example,the metallic material may be nickel based alloy. Further, according toother alternative embodiments, the hanger 32 may be formed of othermaterials such as relatively lower coefficient of thermal expansionmaterials. One such material may be a ceramic matrix composite or othercomposite material, where strength/load requirement, temperature andoperating conditions allow for the use of such material.

Located within the cavity 46 of the web 42 is a shroud 50. The shroud 50has a lower surface 59 which defines a flow path boundary for theturbine 20 (FIG. 1). The shroud 50 is retained in the cavity 46 in theradial direction by an arm 45 (FIG. 3). The arm 45 may be formed in oneor more sections which may be integrally formed or may be joined insubsequent manufacturing steps. The arm 45 depends from the lowersurface 59 of the web 42 and extends in an axial direction. The shroud50 is formed with a pocket 56 (FIG. 3) which received the arm andretains the shroud 50 in a desired position in the radial direction. Theshroud 50 includes a slash face 54 which may engage the arm 45 so as tolimit circumferential movement of the shroud 50 within the cavity 46.

Spaced in the aft direction of the shroud 50 is a retainer 60 which isconnected to the radially inward end of the second leg 41. The retainer60 may or may not be considered a portion of the hanger 32. The retainer60 may have various forms but includes a surface 62 which defines a seatfor a spring seal. According to the instant embodiment, the retainer 60has an inverted “h” shape, but this is not limiting. The retainer 60 maybe connected to the second leg 41 by a c-clip 70.

Referring now to FIG. 3, the shroud hanger assembly 30 is shown in sidesection view. The shroud hanger assembly 30 includes hanger 32, shroud50 and a seal 47. As previously described, the hanger 32 includes firstand second tabs 38, 40 which function to connect the assembly 30 to anengine casing. Depending from the first tab 38 is a first leg 39 and asecond leg 41 depends from the second tab 40. A web 42 extends betweenthe first leg 39 and the second leg 41 and tab 40. The web 42 is shownhaving a linear shape. The web 42 may be formed of a linear structurewhich is angled or which may be axial in extension. Further, accordingto some embodiments, the web 42 may be formed of two or more linearsections or may be curvilinear or a combination of curvilinear or linearsections. The web 42 extends in a circumferential direction to define anarcuate segment of preselected circumferential length defining thehanger segment in part.

Depending from the web 42 is an arm 45 which extends downwardly. The arm45 may depend in a radial direction or at some angle to the radialdirection of the engine. The arm 45 is defined by the first portion 44which extends downwardly and a second portion 48 which extends in anaxial direction. The second arm portion 48 may include a shoulder 49wherein the arm provides a retaining feature for the shroud 50.

The shroud 50 is shown having a shroud base 59 and an upstanding shroudportion 58 and an axial shroud portion 57. The axial and radial portions57, 58 may be formed integrally with base 59 and may have variousshapes, one of which may be an L-shaped feature. The radially extendingportion 58 of the shroud 50 has a length such that the axial portion 57is engages the shoulder 49 and positions the shroud 50 in a radiallyacceptable location relative to the turbine blades which rotate beneaththe base 59. The radial and axial portions 58, 57 in combination withthe base 59 define a pocket 56 wherein the arm 45 is at least partiallypositioned. Thus, the arm 45 functions as an integral radial locator forthe shroud 50 and also inhibits removal of the shroud 50 from the cavity46 of the hanger 32.

In order to retain the arm 45 properly positioned within the pocket 56,one or more springs may be used to provide either or both of axial andradial force. Positioned above the shroud 50 and depending from the web42 is an assembly spring 80. The spring 80 places a downward force onthe upper portion 57 of the shroud 50 forcing it downwardly against thearm 45, and specifically the shoulder 49. Further, a conformal seal 47is depicted engaging the radially extending portion 58 of the shroud 50.The seal 47 forces the shroud 50 in an axially forward direction so thatthe arm 45 remains engaged within the pocket 56 and the shroud may notunintentionally be removed from this engagement. The conformal seal 47is shown as a W-shape in cross section, having linear segments andangled peaks and valleys. However, the spring may also have curved peaksand valleys as an alternative. Other forms of biasing springs areutilized which also form a seal type structure in annular form andpreclude undesired air leakage between the hanger 32 and the shroud 50.Further, while two springs are shown, the springs may include two axialsprings or other biasing forms.

Depending from the second leg 41 is a foot 43 such that the foot 43 andleg 41 form a non-limiting L-shape structure. Depending from the foot 43is the retainer 60 which has a generally H-shaped configurationincluding the engagement surface 62 for engagement of conformal seal 47.The retainer 60 and leg 41, including foot 43, are retained together bya c-clip 70. The clip 70 engages both structures and retains suchstructures together by interference between the two structures providinga solid structure against which the seal 47 may bias shroud 50.

Referring now to FIG. 4, an isometric view of the hanger 32 is shownfrom a lower view looking upward. Within the cavity 46, the arm 45depends from the web 42 and includes an open volume 55 wherein flowingair passes through the hanger 32 to the baffle 52. The baffle 52 may bedisposed beneath the arm 45 or within the volume 55. In this view, abaffle seat 81 is located on the aft surface of the first leg 39. Thebaffle seat 81 is an arcuate groove extending through the first leg 39from the first circumferential end to the second circumferential end.Alternatively, the baffle seat 81 may extend chordally. According tosome embodiments, the seat 81 may extend from one end of the hanger 32to the opposite end or may be formed in one or more segments. The volume55 may be in flow communication with cooling apertures extending throughthe hanger 32.

Referring now to FIG. 5, the shroud 50 is shown. In this view, thepocket 56 is depicted beneath the portion 57 and between the slash facewalls 54. The pocket 56 receives flow communication from the baffle 52(FIG. 3) such that at least the forward portion of the shroud 50 may becooled. The shroud 50 further comprises an overhang 53 which is locatedrearward or aft of the radial portion 58 of the shroud 50.

According to other embodiments, the shroud 50 may have pockets extendingin an aft direction so as receive an arm from an aft extending forwardposition in addition to or alternatively to the arm design depicted.Further to this embodiment, a spring may be located at a forwardposition of the shroud 50 so as to bias the shroud 50 rearwardly ontosuch alternative arm design.

Referring now to FIG. 6, a side section view of an alternate embodimentis depicted. The alternate embodiment comprises a shroud hanger assembly130. As previously indicated, the hanger 132 may be formed of one ormore parts to define a multi-piece hanger assembly. In the instantembodiment, a first hanger portion 134 includes tabs for connecting thehanger 132 to an engine casing. The lower portion of the assembly 132includes arms or retainers 144, 145. The first hanger portion 134 isseated against the retainers 144, 145 and clipped together with a C-clip170. The retainers 144, 145 may take various forms but each include anaxially extending portion 148 and a shoulder 149. The retainers furthercomprise spring seats 162 which according to exemplary embodiments,depend in a radial direction from the shoulders 149 and axial portions148. According to some embodiments the retainers 144, 145 may beintegrally formed with the first hanger portion 134 or alternatively,may be formed separately and joined together in various fashions asdepicted. Conformal springs or seal springs 147 extend from the springseats 162 to a shroud 150.

As discussed previously, the shroud 150 may take various forms andaccording to the instant embodiment the shroud 150 includes first andsecond pockets 156, 157. According to the instant exemplary embodiment,the shroud 150 is I-shaped in cross-section so that the two pockets 156,157 are forms on forward and aft sides of a web 151. Various forms ofcross-sectional shapes may be utilized to allow for application of twoor more pockets on the shroud. Further, the pockets may be aligned inthe axial direction or may be offset circumferentially along the axialdirection.

The foregoing description of several embodiments of the invention hasbeen presented for purposes of illustration. It is not intended to beexhaustive or to limit the invention to the precise steps and/or formsdisclosed, and obviously many modifications and variations are possiblein light of the above teaching. It is intended that the scope of thedisclosure and all equivalents be defined by the claims appended hereto.

What is claimed is:
 1. A shroud hanger assembly, comprising: a shroudhanger having a forward leg, a rearward leg and a hanger web extendingbetween said forward and rearward legs; a plurality of retainersdepending from said forward and rearward legs, respectively, each of theplurality of retainers having an axially extending portion; a shroudformed of a low thermal coefficient of thermal expansion materialextending from said forward leg toward said rearward leg and definingopposing pockets on opposing sides of a shroud web, each pocket forreceiving one of said axially extending portions of each of theplurality of retainers; and opposing conformal seals applying opposingaxial forces to the shroud web in an axial direction to maintain saideach of plurality of retainers in their respective pockets.
 2. Theshroud hanger assembly of claim 1, wherein said shroud hanger is aone-piece hanger.
 3. The shroud hanger assembly of claim 1, wherein saidshroud hanger is a multi-piece hanger.
 4. The shroud hanger assembly ofclaim 1, wherein said low coefficient of thermal expansion material isceramic matrix composite (CMC).
 5. The shroud hanger assembly of claim1, wherein each of said plurality of retainers is a separate componentconnected to said shroud hanger.
 6. The shroud hanger assembly of claim1, wherein each of said plurality of retainers is clipped to said shroudhanger.
 7. The shroud hanger assembly of claim 1, wherein the opposingpockets comprises a first, forward facing pocket and a second, rearwardfacing pocket.
 8. The shroud hanger assembly of claim 7, wherein saidshroud is I-shaped.
 9. The shroud hanger assembly of claim 1, whereinsaid opposing conformal seals are aligned in an axial direction.
 10. Theshroud hanger assembly of claim 1, wherein said opposing conformal sealsact in an aft to forward direction.
 11. The shroud hanger assembly ofclaim 1, wherein said shroud hanger comprises a first hanger portion.12. The shroud hanger assembly of claim 1, wherein the shroud hangercomprises tabs for connecting the shroud hanger to an engine casing. 13.The shroud hanger assembly of claim 1, wherein a lower portion of theshroud hanger comprises the plurality of retainers.
 14. The shroudhanger assembly of claim 11, wherein the first hanger portion is seatedagainst the plurality of retainers and clipped together with a C-clip.15. The shroud hanger assembly of claim 1, wherein each of the pluralityof retainers comprise a shoulder.
 16. The shroud hanger assembly ofclaim 15, wherein the plurality of retainers each comprise a spring seatthat depends in a radial direction from the shoulders and the axiallyextending portions.
 17. The shroud hanger assembly of claim 16, whereineach of the opposing conformal seals extend from the spring seatstowards the shroud.